| 1. |
- Giossi, Rocco Libero, 1991-, et al.
(författare)
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Active Modal Control of an Innovative Two-Axle Vehicle with Composite Frame Running Gear
- 2021
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Ingår i: IAVSD 2021. - Cham : Springer Science and Business Media Deutschland GmbH. ; , s. 8-17
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Konferensbidrag (refereegranskat)abstract
- Within the Shift2Rail projects Pivot2 and NEXTGEAR, an innovative Metro vehicle with single axle running gear and only one suspension step is proposed. A composite material running gear frame is developed to be used both as structural and as suspension element. The design with only one suspension step can significantly degrade the passengers ride comfort. Thus, active modal control is implemented both in lateral and vertical direction to increase the performance of the system. The running gear frame is modelled in Abaqus® as well as the carbody. Structural modes of both elements are implemented in SIMPACK®. A hydraulic actuator model is developed in Simscape®, where two pressure-controlled valves are used to control the pressure inside the chambers of a double acting hydraulic cylinder. A co-simulation environment is then established between SIMPACK® and Simulink®. The vehicle is running with speeds between 10 and 120 km/h. Active modal control makes it possible to maintain ride comfort levels of conventional bogie vehicles with this innovative single axle and single suspension step running gear, promising substantial weight savings of about 400 kg/m. The single axle running gear solution with active comfort control developed here can be an attractive alternative to bogies, providing reduced Life Cycle Costs.
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| 2. |
- Giossi, Rocco Libero, 1991-, et al.
(författare)
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Towards the realization of an innovative rail vehicle - active ride comfort control
- 2022
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 129
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Tidskriftsartikel (refereegranskat)abstract
- The Shift2Rail project Pivot2 introduces an innovative metro vehicle with two single axle running gears with only one suspension step to reduce the vehicle's weight. A U-shaped connection frame is designed in Carbon Fibre Reinforced Polymer to further reduce weight and incorporate the anti-roll bar. Due to the poor ride comfort of the vehicle with standard passive dampers, all six dampers are replaced by hydraulic actuators. Modal control is applied and optimized with genetic algorithms. Despite the good improvements obtained, the weighted vertical acceleration remains above the acceptance level. Two modifications of modal control are studied, i.e., modal control with additional sensor, and blended control. Based on the frequency response of the results, it is proposed a low-pass filtered blended controller to neglect frame accelerations high frequency content. This last improves vertical comfort at the expenses of a more complex control system in comparison to modal control.
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| 3. |
- Mao, Huina, et al.
(författare)
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Design and analysis of laminates for self-deployment of viscoelastic bi-stable tape springs after long-term stowage
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Annan publikation (populärvet., debatt m.m.)abstract
- Bi-stable tape springs are ultra-thin fiber-reinforced polymers composites, which could self-deploy through releasing stored strain energy. Strain energy relaxation is observed after long-term stowage of bi-stable tape springs due to viscoelastic effects and the tape springs might lose their self-deployment abilities. In order to mitigate the viscoelastic effects and thus ensure self-deployment, different tape springs were designed, manufactured and tested. Deployment experiments show that a 4-layer, [-45/0/90/45], plain weave glass fiber tape spring has ahigh capability to mitigate the strain energy relaxation effects to ensure self-deployment after long-term stowage in a coiled configuration. The two inner layers increase the deployment force and the outer layers are used to generate the bi-stability. The presented 4-layer tape spring can self-deploy after more than 6 months of stowage at room temperature. A numerical model was used to assess the long-term stowage effects on the deployment capability of bi-stable tape springs. The experiments and modeling results show that the viscoelastic strain energy relaxationstarts after only a few minutes after coiling. The relaxation shear stiffness decreases as the shear strain increases and is further reduced by strain energy relaxation when a constant shear strain is loaded. The numerical model and experiments could be applied in design to predict the deployment force of other types of tape springs with viscoelastic and friction effects included.
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| 4. |
- Mao, Huina, et al.
(författare)
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Design and Analysis of Laminates for Self-Deployment of Viscoelastic Bistable Tape Springs after Long-Term Stowage
- 2017
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Ingår i: Journal of applied mechanics. - : ASME Press. - 0021-8936 .- 1528-9036. ; 84:7
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Tidskriftsartikel (refereegranskat)abstract
- Bistable tape springs are ultrathin fiber-reinforced polymer composites, which could self-deploy through releasing stored strain energy. Strain energy relaxation is observed after long-term stowage of bistable tape springs due to viscoelastic effects and the tape springs might lose their self-deployment abilities. In order to mitigate the viscoelastic effects and thus ensure self-deployment, different tape springs were designed, manufactured, and tested. Deployment experiments show that a four-layer, [â '45/0/90/45], plain weave glass fiber tape spring has a high capability to mitigate the strain energy relaxation effects to ensure self-deployment after long-term stowage in a coiled configuration. The two inner layers increase the deployment force and the outer layers are used to generate the bistability. The presented four-layer tape spring can self-deploy after more than six months of stowage at room temperature. A numerical model was used to assess the long-term stowage effects on the deployment capability of bistable tape springs. The experiments and modeling results show that the viscoelastic strain energy relaxation starts after only a few minutes after coiling. The relaxation shear stiffness decreases as the shear strain increases and is further reduced by strain energy relaxation when a constant shear strain is applied. The numerical model and experiments could be applied in design to predict the deployment force of other types of tape springs with viscoelastic and friction effects included.
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| 5. |
- Shipsha, Anton, 1988-
(författare)
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Compressive Failure of NCF Composites
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The necessity to reduce environmental impact promotes transportation industry to reduce energy consumption of vehicles. One possible way to improve vehicles' structural efficiency is to utilize modern composite materials that offer excellent mechanical performance-to-weight ratio. Mass production of composite parts requires cost effective manufacturing methods. One potential rational method is to use dry textile preforms and liquid moulding methods, e.g vacuum infusion or resin transfer moulding. Among different types of textile preforms, non-crimp fabrics (NCFs) are most attractive for load bearing applications as they offer considerably higher in-plane mechanical properties compare to other textiles such as wovens or random mats. Composites manufactured with NCF fabrics are characterised by distinct fibre bundles separated by resin rich areas. These bundles are not perfectly straight but have a small yet significant waviness, both in-plane and out-of-plane. The waviness will influence the performance of NCF composites and especially the compressive properties. Design of structural parts made of NCF composites requires both a thorough understanding of the compressive failure process and effective failure prediction models. This is particularly relevant for the critical compressive loaded parts, such as bolted joints.The present work is concerned with the compressive failure of NCF composites and focuses on two major goals. First is to experimentally characterise the compressive failure process of various NCF composites and identify relevant damage modes and mechanisms. Secondly is to develop and propose suitable failure prediction models for reliable design of NCF composite parts with special emphasis on cost-effective methods relevant for industrial design processes.In the present work, a combination of experimental studies, modelling methods development and implementation of advanced state-of-the-art failure criteria have been performed. Optical methods were used to characterise the damage mechanisms in the material at different stress levels. This allowed both identification of the critical damage mechanisms and the whole damage progression sequence. Engineering models were developed to predict the compressive failure of NCF composites. In the models, the fibre bundles' waviness was dealt with in a cost-effective way. The models utilise a state-of-the-art failure criteria that predict both intra-laminar and inter-laminar damage. The proposed models demonstrated good accuracy in the predictions of both compressive and bearing failures. In addition, a cost-effective high-fidelity meso-scale modelling methodology was developed for bearing failure prediction of NCF composites. The methodology demonstrated a potential for cost-effective and highly detailed analysis of the bearing failure process and possible method for parameter studies of mechanical properties and their relation to the reinforcement architecture.
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| 6. |
- Shipsha, Anton, et al.
(författare)
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Effect of stacking sequence and bundle waviness in quasi-isotropic NCF composites subjected to compression
- 2019
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Ingår i: Composites Part B. - : Elsevier. - 1359-8368 .- 1879-1069. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- The current study is focused on the compressive strength of composite materials containing non-crimp fabric (NCF) reinforcement, and how ply stacking sequence and fibre waviness influence onset and growth of damage in such materials. Experiments reveal significant effects from stacking sequence, both on the compressive strength as such, and on the underlying failure mechanisms. The fibre waviness also has a strong influence on the strength. Fibre kinking is seen before ultimate failure for all configurations but some of them also show local delamination prior to kinking. A finite element simulation methodology is developed and used for the studied cases. It handles local variations of fibre orientations by corresponding re-orientation of stiffness matrices at element level. The simulations provide good predictions of intra- and inter-laminar failure considering both in- plane and out-of-plane fibre bundle waviness. The model is further used in a parametric study of the influence from bundle waviness on the compressive strength.
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| 7. |
- Shipsha, Anton, et al.
(författare)
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Failure mechanisms in NCF composite bolted joints : Experiments and FE model
- 2020
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Ingår i: Composites Part B. - : ELSEVIER SCI LTD. - 1359-8368 .- 1879-1069. ; 192
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Tidskriftsartikel (refereegranskat)abstract
- The current study focuses on the bearing failure process of NCF composites and associated damage mechanisms. A set of experiments on bolted joints between NCF composite and steel plates have been performed. The bearing damage onset and failure progression in the composite was monitored at different load levels by microscopic image analysis. Fibre kinking in 0 degrees. layers was found as the key damage mechanism that initiates and drive the bearing failure. Matrix cracking and delaminations were found as well. A cost-effective FE model that predicts bolt bearing failure of NCF composites was proposed. The model utilises state-of-the-art failure criteria and predicts both intra- and inter-laminar progressive damage. A good correlation between the predicted damage development process and experiments was observed both in terms of failure modes and load levels.
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| 8. |
- Shipsha, Anton, 1988-, et al.
(författare)
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Failure mechanisms in NCF composite bolted joints. Experiments and FE model
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The current study focuses on the bearing failure process of NCF composites and associated damage mechanisms. A set of experiments on bolted joints between NCF composite and steel plates have been performed. The bearing damage onset and failure progression in the composite was monitored at different load levels by microscopic image analysis. Fibre kinking in 0° layers was found as the key damage mechanism that initiate and drive the bearing failure. Matrix cracking and delaminations were found present as well. A cost-effective FE model that predicts bolt bearing failure of NCF composites was proposed.The model utilises state-of-the-art failure criteria and predicts both intra- and inter-laminar progressive damage. A good correlation between the predicted damage development process and experiments was observed both in terms of failure modes and load levels.
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| 9. |
- Shipsha, Anton, et al.
(författare)
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Failure of cross-ply NCF composites under off-axis compressive loads - An experimental study and a new strength prediction model including fibre bundle waviness
- 2018
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Ingår i: Composites Part B. - : Elsevier. - 1359-8368 .- 1879-1069. ; 153, s. 49-56
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Tidskriftsartikel (refereegranskat)abstract
- The design of reliable and efficient mechanical joints with non-crimp fabric (NCF) composites depends on several factors but knowledge on actual loading direction and an accurate compressive strength prediction is essential. Motivated by this, the current study is focused on the compressive strength of cross-ply NCF composites and the influence of fibre orientation in relation to the loading direction. Possible influence of stacking sequence on the compressive strength is also studied. Compression tests of cross-ply NCF composite laminates that are loaded at various off-axis angles are performed and the failure mechanisms are identified. An analytical semi-laminar based model for strength prediction of NCF composite laminates loaded in compression is then suggested. The model take in- and out-of-plane bundle waviness into account. Good agreement between the proposed model and experiments is observed.
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| 10. |
- Shipsha, Anton, et al.
(författare)
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Failure prediction model for ncf laminates loaded in compression and the effect of off-axis loading
- 2015
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Ingår i: 20th International Conference on Composite Materials, ICCM 2015. - : International Committee on Composite Materials.
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Konferensbidrag (refereegranskat)abstract
- Design of reliable and efficient mechanical joints with non-crimp fabric (NCF) composites depends on accurate compressive strength prediction. Motivated by this, the current study is focused on the compression strength of NCF and the effect of fibre orientation in relation to the loading direction. Influence of stacking sequence on the compressive strength is studied as well. An experimental methodology is developed based on the classic IITRI test setup complemented with digital speckle photography (DSP) for accurate strain measurements. Compression tests of NCF composite laminates loaded at various off-axis angles are performed for different lay-ups. An engineering model for strength prediction of NCF composite laminates loaded in compression is suggested. Good agreement between the proposed model and the experiments was observed.
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| 11. |
- Shipsha, Anton, 1988-, et al.
(författare)
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Meso-scale modelling of the bearing failure in NCF composites
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The study is focused on the bearing failure of NCF composites. The study presents a cost-effective methodology for high-fidelity meso-scale modelling of NCF composites and bearing failure prediction. The proposed methodology does not require expensive measurements of the meso-structure, nor access to specimen of the material. Instead, the complex meso-structural geometry in the model is achieved by the included compaction analysis of a dry multi-layer NCF preform. The modelling process is assisted by the developed Python-based automated framework. The methodology was applied to predict bearing failure of the experimentally tested pin-loaded quasi-isotropic NCF composites. A good agreement of the predicted and measured meso-structural geometry was found. The proposed method could accurately predicted the meso-structural geometry of the manufactured NCF composite in terms of both tow paths and their cross sectional shapes. The predicted bearingfailure response was found to be in general agreement with experiments. However, predictions of damage initiation and progression were too conservative. This is explained by the conservatism of the material properties used and material model.
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